A series of investigations have found that raising circulating glucose levels can improve memory performance in animals, healthy humans and patients with schizophrenia and Dementia of the Alzheimer's type (DAT). Elevations of plasma insulin alone, using a hyperinsulinemic euglycemic "clamp", can also increase memory performance in DAT, suggesting the importance of intracellular glucose availability. This 3 year project will assess the dose-response relationship of insulin & memory performance in humans, & will investigate age-related changes.